Applied Research Of Pile Load Transferring Function On Churning Driven Cast-in-place Pile

During the pile foundation design, the pile's bearing ability and its sedimentation property are the important indices which should be first determined. Although the pile foundation is a kind of foundation which is now most widely used at home or abroad, the pile-soil system is a very complex mechanical system and its engine6ring design method is still in a semi-theory and semi-experience state up to now. The bearing ability formula now adopted by the norm is basically established by the simple algebraic addition of the pile-side frictional resistance and the pile-end resistance, this can't reflect the pile's load transferring properties. On the other hand, with the development of electronic technology and computing method, the numerical (for instance, finite element method) is used to analyze the pile's engineering properties and some research results have been got. This method can fully simulate the mutual action mechanism of the pile-soil, however, the computing parameters can't be easily determined, the relation between the computing results and the influencing factors isn't directly perceived, thus, it can't be widely used in the engineering practice. In order to reflect the main work mechanism of the pile-soil system, the computing-analysis method isn't too complex, many engineering technicians and researchers have paid attention to the study on the properties of the pile's load transferring function in recent years. On the basis of the used load transferring function, the pile's load-sedimentation curve can be got by some simple data's operation,thus, the mechanical performance of a single pile and a group of piles can be analyze .In this paper, the author has analyze and summarized the load transferring mechanism of a single pile, deeply and carefullyexpounded all the aspects of the properties of the resistance at the sideof the pile and at the end of the pile, summarized the load transferring course and law of the pile-soil system under vertical load, listed the load-sedimentation (Q-s) curve often used in the engineering practice, and emphatically analyze the load transferring properties of the cast-in-place pile.In the paper, the author has analyze and discussed the various kinds of methods of computing the single-pile load-deformation,concretely analyze the load transferring function and according tothe different ways of working out the basic differential of the load transferring function, introduced three methods of computing the load transferring function, and summarized some pile-body and pile-end load transferring function put forward by some research scholars at present.The author has introduced the special process characteristics of the cast-in-place pile by churning driven. According to the static loadtest and the pile body stress test results of many cast-in-place pilesby churning driven in some special strata area, the author has analyze the pile's vertical load transferring properties and the pile-side or pile-end bearing ability traits, summarized the ultimate bearing ability features of the vertical load of a single pile and pointed out that thebearing ability features of the cast-in-place pile by churning driven in the special strata area are different from that of the common cast-in-place pile after comparing the computing results with pile foundation norm.On the basis of the actual measurement data for the casl-in-place piles by churning driven in the special strata area, the author has made a study on the pile side frictional resistance transferring function law, probed into the theoretical computing method of the model parameters, and established the load transferring function computing method fit for the soil features in this area and the process conditions according to the comparison between the theoretical computing and actual measurement results, It is reliable and feasible to use load transferring function method to compute the Q-s curve of a single pile.